The present invention relates to a method for terminating a cable having a thermosetting resin layer and an apparatus used for the termination of cable
Construction of cable will be explained prior to explanation of conventional techniques.
As shown in FIG. 12 and FIG. 13, cable 10 is formed of signal wire 1 and ground wire 2 in pairs and a plurality of them are arranged in parallel.
Signal wire 1 is covered with inner foamed insulant 3 for improvement of signal propagation and due to limitation in impedance characteristics.
Ground wire 2 is provided adjacent to signal wire 1 covered with inner foamed insulant 3 and this ground wire 2 and signal wire 1 together are wound and covered with Al shielding tape 4 and are further covered with outer insulant 7 formed of fluororesin (FEP) which is a thermoplastic resin.
Al shielding tape 4 generally comprises Al foil 5 coated with polyester resin 6 which is a thermosetting resin on outer surface thereof.
One method for terminating such cable is disclosed, for example, in Japanese Patent Kokai No. 62-58809.
According to the above conventional technique, outer insulant is cut and peeled by a jacket peeling blade to expose Al shielding tape 4 and then, Al shielding tape 4 is cut and peeled by a tape peeling blade 8 having a specific flat portion formed on the end portion as shown in FIG. 14 and FIG. 15 for decreasing damage of inner foamed insulant 3.
The conventional method for terminating cables is superior in that inner foamed insulant 3 is not directly damaged by tape peeling blade, bus has the following problems.
That is, as shown in FIG. 17, in order to ensure insulation in connecting conductor 9a on substrate 9 with cable 10, insulation spacing Lb between terminal 4a of Al shielding tape 4 and terminal 9b of conductor 9a must be kept at more than a certain value. According to conventional technique, the flat part of tape peeling blade 8 is pressed to Al shielding tape 4 to tear off tape 4 and so residual length La which is the length between terminal 7a of outer insulant 7 and terminal 4a of Al shielding tape 4 is large as shown in FIG. 18 and besides, variation of the length is great and in some case the insulation space Lb cannot be sufficiently maintained.
Furthermore, as shown in FIG. 16, there are problems that fragments 4b of Al shielding tape are scattered owing to tearing off of Al shielding tape 4 and since tape peeling blade is pressed to Al shielding tape 4, inner foamed insulant 3 might be indirectly damaged and thus sufficient insulation cannot be ensured.
There are further problems that correction of terminal 4a of Al shielding tape 4 requires time due to variation of residual length of Al shielding tape 4 and besides, size of connector and the like provided at terminal portion of cable must be large considering variation of residual length.
Further problems are that size of flat portion of tape peeling blade 8 must be controlled and in addition, in order to cut inner foamed insulant 3 without severe damage thereof, minimum gap G between upper and lower tape peeling blades must be severely controlled and this is troublesome.